onnxruntime

72bce1df - [WebGPU] Correct MatMul bias input indexing in `MatMul::ComputeInternal` (#28475)

[WebGPU] Correct MatMul bias input indexing in `MatMul::ComputeInternal` (#28475) ### Description WebGPU MatMul was wiring bias into the wrong slot in the `inputs` vector when bias is present. The vector is pre-sized to 3 and downstream code reads bias from `inputs[2]`, but the previous logic appended bias, placing it at index 3. - **Root cause** - `inputs` was initialized with size `3` for bias cases, then bias was added via `push_back`, creating a 4th element. - **Change** - Replaced append logic with direct assignment to the expected index. - **Effect** - Bias is now consistently passed at `inputs[2]`, matching `ComputeMatMul()` and Intel-path expectations. ```cpp std::vector<const Tensor*> inputs(has_bias ? 3 : 2); inputs[0] = a; inputs[1] = b; if (has_bias) { const auto* bias = context.Input(2); inputs[2] = bias; // was: inputs.push_back(bias); } ``` ### Motivation and Context This addresses incorrect bias propagation in WebGPU MatMul (`onnxruntime/core/providers/webgpu/math/matmul.cc`) caused by index mismatch between producer and consumer logic. The fix is intentionally surgical: one behavioral line change in the affected code path. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: guschmue <22941064+guschmue@users.noreply.github.com>